Background specs:

Car: 2000 Corvette FRC (Fixed Roof Coupe)
Engine: LQ9 Iron Block 408ci
Misc. engine specs as-is:
4 callies crank
eagle rods
diamond pistons
ATI damper pulley
Absolute speed heads W/ 2.08 1.60? valves flow 325+
custom ground cam its a 244 248, 61x 61x 114
Comp r lifters
Hardened push rods (7.350" Trick Flow)
C.R 11.6
90mm fast intake and TPIS 90MM TB.
38# injectors
Granettelli maf

(dynoed 519.9 rwhp / 486 ft-lbs)

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Background info:

I was planning on swapping the valve springs in the car as I had some loud top end ticking type noise that had gotten pretty loud recently and its around the 30k miles mark for them. So I started to tear down the engine when I see the top of one of valve stems is smashed and the rocker for that valve is also damaged. Now I have to take off the heads and thus all the crap in the front/drain the coolant...yadda yadda.


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Currently on my install list:

Patriot Stage III heads with valves/dual springs good for .650" of lift. (https://www.patriot-performance.com/...&cat=35&page=1)
LS6 PCV setup
New roller rockers (brand/type unknown, suggestions welcome)
Ported oil pump (unless mine is already ported)

Possibly new push rods, length/type unknown, possibly a new cam.


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CAM talk:

I'm thinking about swapping the cam for something more street friendly/warm weather friendly. The car runs very good in moderate to cool S. Fla weather. But in the dead of summer it struggles to idle with the AC on, with the AC off it is fine. But the car is black and its FL so its like 130*+ in the car with the AC off. Basically when its really hot and the engine is warm and the AC is on the rpms will start bouncing around when sitting and idling (meaning it will drop 100 rpms off idle then rev to 100 over and continue until its dropping to 500 rpms and revving to 1500rps on its own). Also another issue is if you start to give it a little gas and slip the clutch just to move a little or to make a U-turn etc the engine sometimes stalls when you suddenly push the clutch in and take the load off the engine. Driving it is fine and runs the AC no problem. A hole in the throttle body would probably somewhat eliminate the issue as you can keep it from rev jumping by applying just a hair of pressure on the gas pedal but I really don't want to do that. Also its been tuned by more then 1 tuner same issue stays.

I'm also kind of looking for a different sound, the sound right now has been described by the police and others as sounding like "an outboard motor out of water" or like a "powerboat".

Current cam idle: http://www.youtube.com/watch?v=P836CE-ag5M
Current cam low rev: http://www.youtube.com/watch?v=Dh3hoMvxM8g

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Looking for suggestions on what to add, specific parts for what I already plan on changing out, general suggestions etc. Lemme hear it. :wavey:

 

Just have the valves replaced on the heads that you have, no reason to switch to some other port profile when you already have a set that makes good power. Drop the cam down a stage if you want, but really your problem is with your tuner and cooling system.

 

Nothing wrong with that cam. It's a commonly used spec for lots of 408 engines and since it's not too radical it will behave, given someone who knows how to make it do so. I'm running a cam with 4-5 degrees less duration in my 346 and don't have any stalling or idle problems with or without the AC.

And I would try to find out what caused the damage to the valvetrain. Possible lack of oil? Pushrod? Lifter?

And as long as you have a stock casting head, the stock rocker will work fine. Or better yet have Harland Sharp rebuild the stockers for you.

 

First off thanks for the replies.


I'm not too terribly concerned with loosing some power. However I think I'm not going to update the cam as what I have seems pretty standard for a big block and although I'm not real worried about power I don't want to 'cut off my legs' so to speak and drop the power level down to the low 400's either. Also you have to drop the steering rack to change it, screw that. :emb:


On the issue of heads the reason I was considering the patriot heads was not as an upgrade but just to simplify things as the heads would be clean and new with valves/valvesprings already installed. I figured they would lower my compression ratio a bit but that didn't concern me too much. Also just running the numbers as long as I could sell the heads I have now for ~600-650'ish it would be a breakeven thing. How hard is it to install valves anyway? any special tools needed?

 

If you're worried about losing power then the Patriot heads may not be your best choice. The Absolute Speed stuff is pretty good, and from what I've seen nowhere near the Patriot heads. Your current combo already makes good power, so why change it to a head with a bad rep? Changing the valves is fairly easy. Once the heads are off the car all you need is a valve spring compressor - the large clamp type work best with heads off the car. Make sure to check your springs and valve guides if you go that route! Get some valve compound and lightly lap the valves. Or you could have a machine shop replace the valves for you and check everything over. Just an overall check of the springs, guides, and valve replacement is pretty cheap. Don't let them talk you into a valve job though...

 

I would save the money on the heads too, and just get those refreshed. Unless you are going to step up to some Trickflows or ET's, I don't see the power gain for money spent for new factory ported heads.

Also, don't buy your pushrods until your heads are bolted down. There is a place called Trend here in metro Detroit that will get you a set in one day. Get one of those measurement pushrods and get the exact size you need.

-Geoff

 

I actually already have new Valvesprings, retainers, locks etc and the crane cam VS install tool. That was what I was originally doing before I found the damaged valve.


Well if I use the heads I have now which I think I will then the pushrods should be the same length, 7.350.

 

The Crane tool will work, but it is designed to be used with the head on the engine. If the head is off, that leverage design compressor will require the head to be stationary. You will need to bolt the head to somethig.

 

You will need to be careful if doing it yourself with that damaged valve - do not try and force it out the guide, use a file and spin the valve with the file on the tip to remove the mushroomed material and keep from destroying your guides. Guides are just like a cylinder bore but with a smaller dimension but the same precision - scars/grooves down the guide can lead to oil consumption.

 

Did you measure when you put them in? Push rods that are too short can lead to valve damage. They can make a ticking noise too, which you described hearing. I am just saying...

-Geoff

 

I bought the car modified and these pushrods have been in the car for about ~28,000 miles. I didn't begin to hear the noise until recently. I see the pushrod length checking tool but how is it used?

 

I decided to keep the heads I have and to not update the cam or oil pump.

My shopping list, please check for missing stuff (click for link):

Main parts:
LS7 Lifters
Yella Terra Roller Rockers for LS2, L76, L92 & L98
Are there other strong but cheaper valves in the 2.08/1.60 size?
Manley Race series intake valves 2.08
Manley race series exhaust valves 1.60
LS6 PCV conversion kit
160* Thermostat


Already purchased
Dual Spring Kit w/ locks, retainers and intake/exhaust valve seals

Gaskets/Seals
LS2 Head gasket, x2
FAST Intake seals
GM water gasket

Misc unlinked:
7 quarts oil + filter
Coolant

If its not listed I didn't consider it so I'm missing a gasket or similar please list it. Do I need to replace my head bolts? Also another site recommended replacing the lifter trays, should I? Do I have all the seals I need for the valves?

Thanks.

 

Factory head bolts must be replaced every t1me they are removed.
ARP bolts or studs are reusable. Your motor may already have them.

For me the studs seemed the best way to go as you never have to clean out the bloc threads aga1n and the nuts turn on the stud 1nstead of the bolt turn1ng 1n the alum1num bloc.

 

The Yella Terra rockers and LS6 PCV conversion are adding unnecessary costs. Stock rockers work fine for just about any hydraulic roller build possible. And the LS6 PCV conversion usually does nothing for oil consumption if that's the reason for purchasing. A quality catch can will work better.

LS2 lifter trays are highly recommended. Their very cheap and offer extra insurance against cracking and allowing a lifter to spin.

AL SS590 M6 - does your "I" key not work?

 

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No eye cay e1ght or comma. Eye need a new laptop